A car struck a pedestrian in Whalley Road shortly before 1pm on Thursday (March 10).
The pedestrian, a man in his 80s, suffered “serious injuries” and was pronounced dead at the scene.
A spokesman for Lancashire Police said: “Police remain at the scene carrying out a collision investigation.”
North West Ambulance Service said two ambulances, a MERIT doctor and an air ambulance crew attended.
“A man in his 70s was taken to hospital,” a spokesman for NWAS added.
The road was expected to remain closed for some time.
Motorists were urged to avoid the area, with heavy congestion building on surrounding roads.
A spokesman for Lancashire Police added: “Please find an alternative route and we will update you when we can.”
Anyone with information should call police on 101 quoting log 0577 of March 17.